So-called current mode logic (CML) makes it possible to implement digital logic circuits. CML is based on the differential transmission of logic signals. This makes possible—despite typically low signal amplitudes—good interference immunity.
CML is also suitable for enabling reliable operation at comparatively high frequencies of the logic signals. By way of example, static frequency dividers in the millimeter wave regime are typically implemented using CML.
On the other hand, CML has certain disadvantages and limitations. By way of example, in the case of CML it may be necessary to choose the supply voltage of the voltage supply to be greater than or equal to a minimum value. The minimum value can be defined by the number of required transistors cascaded or stacked one on top of another in circuit branches between the voltage supply and earth. Particularly with the use of bipolar transistors, such as, for example, the heterojunction bipolar transistor (HBT), for instance using silicon germanium (SiGe) technology, the minimum value may have a significant magnitude. By way of example, the supply voltage may be 3.3 V in typical reference implementations.
On account of the significant minimum value for the supply voltage, a corresponding CML circuit may have a high DC power consumption. However, there are many applications in which a comparatively low DC power consumption is desirable.